1. Technical Field
The present invention relates to a capacitance type input device capable of detecting an approach position of a finger by a capacitance variation and a display device with an input function, which includes the capacitance type input device.
2. Related Art
In electronic apparatuses such as mobile telephones, car navigation systems, personal computers, ticket vending machines, bank terminals or the like, recently, there is provided an electronic apparatus in which a tablet input device is arranged on a surface of a liquid crystal device or the like, and a finger or the like is brought into contact with a place where a pointed image is displayed, while referring to the pointed image displayed in an image display region of the liquid crystal device, so as to input information corresponding to the pointed image.
Such an input device (touch panel) includes a resistance film type input device, a capacitance type input device, and so on. Since the resistance film type input device has a double sheet structure including a film and glass and a structure in which a film is pressed to short-circuit, the resistance film type input device has problems such as a narrow operation temperature range and weak time variation.
In contrast, the capacitance type input device has an advantage that light transmission conductive films are formed in one substrate. Such a capacitance type input device includes, for example, an input device in which electrode patterns extend in directions which are perpendicular to each other and a capacitance variation between the electrodes when a finger or the like is contacted is detected so as to detect an input position (for example, see JP-A-11-154053).
When a liquid crystal device or the like is arranged so as to be superposed on the input device, since an image displayed by the liquid crystal device is transmitted from an input surface side of the input device and is viewed, the substrate and the electrode patterns with an excellent light transmission property are used. However, if a region in which the light transmission electrode patterns or the like are formed and a region in which the light transmission electrode patterns or the like are not formed are significantly different from each other in reflectivity, the existence of the light transmission electrode patterns is unpreferably conspicuous.
However, if a first light transmission electrode pattern and a second light transmission electrode pattern are respectively formed on the front surface and the rear surface of the light transmission substrate, since the light transmission substrate is interposed between the first light transmission electrode pattern and the second light transmission electrode pattern, the region in which the first light transmission electrode pattern is formed, the region in which the second light transmission electrode pattern is formed, and the region in which these light transmission electrode patterns are not formed are significantly different from one another in the optical configuration and thus a significant difference among the regions occurs in reflectivity. Accordingly, the existence of the light transmission electrode pattern is conspicuous.
Even when the first light transmission electrode pattern and the second light transmission electrode pattern are formed on the same surface of the light transmission substrate, since a glass substrate which is generally used in the light transmission substrate and an indium tin oxide (ITO) film which is generally used in the light transmission electrode pattern are different from each other in a refractive index, a difference between the region in which the light transmission electrode pattern is formed and the region in which the light transmission electrode pattern is not formed occurs in reflectivity and thus the existence of the light transmission electrode pattern is unpreferably conspicuous.